Crankcase lubricant compositions may be selected to provide an increased engine protection while providing an increase in fuel economy and reduced emissions. However, in order to achieve benefits of improved fuel economy and reduced emissions, a balance between engine protection and lubricating properties is required for the lubricant composition. For example, an increase in the amount of friction modifiers may be beneficial for fuel economy purposes but may lead to reduced ability of the lubricant composition to handle water. Likewise, an increase in the amount of anti-wear agent in the lubricant may provide improved engine protection against wear but may be detrimental to catalyst performance for reducing emissions. Accordingly, there is a need for improved lubricant compositions that are suitable for meeting or exceeding the currently proposed ILSAC GF-5 lubricant performance standards.
In view of the foregoing, the disclosure provides crankcase lubricant that includes a) a major amount of a base oil; b) an alkali or alkaline earth metal-containing detergent; c) a phosphorus-based wear preventative; and d) a surfactant agent other than (b). The lubricant has a weight ratio of alkali or alkaline earth metal content to phosphorus content, based on a total mass of lubricant, ranging from about 1.6 to about 5.0.
In one embodiment, the disclosure provides an additive composition suitable for use in a crankcase lubricant. The additive composition includes a) an alkali or alkaline earth metal-containing detergent; b) a phosphorus-based wear preventative; c) a surfactant agent other than (a); and d) a non-metal friction modifier. The additive composition has a weight ratio of alkali or alkaline earth metal content to phosphorus content ranging from about 1.6 to about 5.0.
Another embodiment of the disclosure provides a method for improving the water tolerance of a crankcase lubricant containing more than about 0.1 percent by weight of a non-metal friction modifier. The method includes combining a major amount of a base oil with an alkali or alkaline earth metal-containing detergent, a phosphorus-based wear preventative, and a surfactant agent having an HLB value ranging from about 4 to about 5.
The following definitions of terms are provided in order to clarify the meanings of certain terms as used herein.
As used herein, the terms “oil composition,” “lubrication composition,” “lubricating oil composition,” “lubricating oil,” “lubricant composition,” “lubricating composition,” “fully formulated lubricant composition,” and “lubricant” are considered synonymous, fully interchangeable terminology referring to the finished lubrication product comprising a major amount of a base oil plus a minor amount of an additive composition.
As used herein, the terms “additive package,” “additive concentrate,” and “additive composition” are considered synonymous, fully interchangeable terminology referring the portion of the lubricating composition excluding the major amount of base oil stock mixture.
As used herein, the term “HLB” means the hydrophilic/lipophilic balance of a surfactant.
As used herein, the term “hydrocarbyl substituent” or “hydrocarbyl group” is used in its ordinary sense, which is well-known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Examples of hydrocarbyl groups include:                (1) hydrocarbon substituents, that is, aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic-, aliphatic-, and alicyclic-substituted aromatic substituents, as well as cyclic substituents wherein the ring is completed through another portion of the molecule (e.g., two substituents together form an alicyclic radical);        (2) substituted hydrocarbon substituents, that is, substituents containing non-hydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbon substituent (e.g., halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy);        (3) hetero substituents, that is, substituents which, while having a predominantly hydrocarbon character, in the context of this invention, contain other than carbon in a ring or chain otherwise composed of carbon atoms. Heteroatoms include sulfur, oxygen, nitrogen, and encompass substituents such as pyridyl, furyl, thienyl, and imidazolyl. In general, no more than two, for example, no more than one, non-hydrocarbon substituent will be present for every ten carbon atoms in the hydrocarbyl group; typically, there will be no non-hydrocarbon substituents in the hydrocarbyl group.        
As used herein, the term “percent by weight”, unless expressly stated otherwise, means the percentage the recited component represents to the weight of the entire composition.
The terms “oil-soluble” or “dispersible” used herein do not necessarily indicate that the compounds or additives are soluble, dissolvable, miscible, or capable of being suspended in the oil in all proportions. The foregoing terms do mean, however, that they are, for instance, soluble or stably dispersible in oil to an extent sufficient to exert their intended effect in the environment in which the oil is employed. Moreover, the additional incorporation of other additives may also permit incorporation of higher levels of a particular additive, if desired.
Crankcase lubricating oils of the present disclosure may be formulated by the addition of one or more additives, as described in detail below, to an appropriate base oil formulation. The additives may be combined with a base oil in the form of an additive package (or concentrate) or, alternatively, may be combined individually with a base oil. The fully formulated crankcase lubricant may exhibit improved performance properties, based on the additives added and their respective proportions.
Additional details and advantages of the disclosure will be set forth in part in the description which follows, and/or can be learned by practice of the disclosure. The details and advantages of the disclosure may be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed.